a(n) = Sum_{k=0..[n/2]} binomial((n-k)*k, k^2).
A228833
a(n) = Sum_{k=0..[n/2]} binomial((n-k)*k, k^2).
Terms
- a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =20a(6) =77a(7) =437a(8) =5509a(9) =54475a(10) =1031232a(11) =31874836a(12) =789351469a(13) =47552777430
External references
- oeis: A228833